Process for the production of alkyl-substituted bicyclo[2.2.1] hept-2-ene



3,240,828 Patented Mar. 15, 1966 United States Patent ice hexylmethanol,cyclopropanol, methylcyclopropanol, cyclopentanol, cyclohexanol,cyclooctanol and the like.

The basic catalysts which are employed are strong bases, such as alkalimetal hydroxides or alkali metal oxides of the alcohols employed in thereaction. The

preferred basic catalysts are sodium or potassium hydroxides or sodiumor potassium oxides of the alcohols.

The mole ratio of alcohol to bicyclo[2.2.1]hept-2-ene in the reactionmixture is not narrowly critical. How- This invention relates to a novelmethod for the alkylaever, it is preferred to employ at least equimolaramounts. tion of bicyclo[2.2.l]hept-Z-ene. More particularly, thisExcess amounts of alcohol can be employed as a reacinvention relates toa simple method for the production tion solvent, if desired. Thecatalytic amount of base of bicycloheptenes substituted on the l-, 2-,3- or 4-poin the initial charge is not narrowly critical and can varysitions. from about 1 to about 10 mole percent based on the al- Prior tothis invention substituted bicyclo[2.2.1]-heptcohol charged. At loweramounts the reaction proceeds 2-enes were generally produced by theDiels-Alder additoo slowly for practical use and, although higheramounts tion of a mono-olefinically unsaturated compound to a can beemployed, no particular advantage is obtained cyclopentadiene, asindicated by the following equation: thereby.

, 3,240,828 PROCESS FOR THE PRODUCTION OF ALKYL-SUB- ST ITUTEDBlCYCLO[2.2.1]HEPT-2-ENE Henry E. Fritz, Charleston, and Kenneth E.Atkins, South Charleston, W. Va., assignors to Union CarbideCorporation, a corporation of New York No Drawing. Filed July 29, 1963,Ser. No. 298,477 8 Claims. (Cl. 260-666) wherein each R is hydrogen or asubstitllent- Because The reaction temperature is not narrowly critical,and of the relative unavailability of substituted cyclopentatemperaturesof from about 150 C. to about 400 C. dienes, this process was normallyemployed to produce have been found suitable. Optimum yields of substi-5- or 6-substituted bicyclo[2.2.1]hept-2-enes. The proctutedbicycloheptenes are obtained at temperatures of ess of this inventionprovides, for the first time, a general. from about 220 C. to 280 C.Because the reaction is simple synthesis of bicycl0[2.2.llhepts Su stitt d a liquid phase reaction, it is desirable to conduct the rein the 1-,2-, 3- and/ or 4-positions from readily available action under elevatedpressure to prevent vaporization starting materials. of the reactants.The reaction time can vary from a The process of this inventionessentially COIIIPIiSBS few minutes up to several hours, depending onhether the r a ti n f Y U- J W With all 31601101, the process isconducted continuously or in a batch-wise as hereinafter defined, incontact with a basic catalyst manner. In general, times of from 1 toabout 10 hours whereby the y l l p -2-ene i u stit t d in the can beemployed in a batch process. Inert reaction me- 1-, 2-, 3-or4-positions. dia, such as toluene, xylene, isooctane and the like canThe alcohols which are employed in accordance with be employed, ifdesired. The products produced by the the process of this invention aremonohydric hydrocarprocess f thi i mio ill vary according t th lbonalcohols free from aliphatic (olefinic and acetylenic) cohol employed inthe reaction. If a primary alcohol is unsaturation wherein the hydroxylgroup is bonded to em lo ed, th i rodu t r monos b tit ted bi- 3. carbonatom having at least one hydrogen atom bonded cycloheptenes, with theZ-isomer predominating, Howthereto, P y and sficolldal'y 316011015-These ever, 1.3-, 1,4-, 1,2,4- and 1,2,3,4-substituted bicycl-o-2116011015 @311 be Teprfiseflted y the formula: heptenes are alsoobtained in small yields. In the other R1 hand, disubstitutedbicycloheptenes are normally obtained when secondary alcohols areemployed, with the 1,3- CHOH isomer predominating. In addition, 1-, 2-and 1,2,4-

32 isomers can be obtained in smaller yields.

The products of the process of this invention are recovered from thereaction mixture by conventional procedures.

The following examples are illustrative.

wherein each R and R when taken alone, can be hydrogen or a hydrocarbongroup free from aliphatic unsaturation, such as alkyl, cycloalkyl oraryl; and R and R when taken together, form a divalent alkanediyl groupwhich, when taken with the CH group, forms a cycloalkyl group of from 4to 8 ring members. In gen- A 3-l1ter, stainless steel, rocker autoclavewas charged eral, the alcohols can have from 1 to about 15 carbon at-With 50 grams of bicyclo[2.2.l]hept-2-ene, 4i grams oms, with alcoholshaving from 1 to about 10 carbon atof approximately 50 percent sodiummethoxide 1n methoms being preferred. As examples of suitable alcoholsone anol and 1 liter of methanol. The autoclave was sealed, can mentionmethanol, ethanol, n-propanol, isopropanol, heated to 235 C. Within 2hours and maintained at n-butanol, sec.butanol, the primary andsecondary pen- 228 C. to 252 C. for 3.2 hours. After cooling to roomtanols, the primary and secondary hexanols, the primary temperature andstoring at room temperature overnight, and secondary octanols, theprimary and secondary decthe reaction mixture was heated to 240 C. 1n2.5 hours anols, benzyl alcohol, phenethyl alcohol, a-methylbenzyl andmaintained at 240 C. to 279 C. for 5.5 hours. The alcohol, a-ethylbenzylalcohol, 3-phenyl-4-octanol, cyclomaximum observed autogenous pressureduring the re- Example I action was 2100 p.s.i. After cooling andopening the autoclave the reaction mixture was filtered to removeinsoluble residues and then admixed with water. The aqueous mixture wasextracted with hexane and the hexane extract was washed with water untilit had a pH of about 7. The water-washed material was distilled torecover 13 grams of a mixture of 1-methylbicyclo[2.2.1]- hept-2-ene andZ-methylbicyclo [2.2.1]hept-2-ene at a temperature of from 104 C. to 125C. This mixture contained predominantly the 2-isomer, as indicated byinfrared analysis.

Example II A l-liter, stainless steel rocker autoclave Was charged with50 grams of bicyclo[2.2.1]hept-2-ene and a solution of 4 grams of sodiumin 260 grams of 2-ethylhexanol. The autoclave was sealed and heated at220282 C. for 4.25 hours, during which time the maximum autogenouspressure observed was 361 p.s.i. The reaction mixture was Washed withwater until a pH of about 7 was achieved, and the water-washed productwas distilled to recover 21 grams of(2-ethylhexyl)bicyclo[2.2.1]hept-2-ene at 83 C. and 0.20 mm. The productconsisted predominantly of the 2-isomer although there was a smallamount of l-isomer present.

Microanalysis.Calculated for C H C, 87.3; H, 12.7. Found: C, 87.1; H,12.7.

Example III Employing apparatus and procedures similar to thosedescribed in Example II, except that 10 grams of potassium hydroxide (85percent pure) were substituted for the sodium there were recovered 17grams of 1- and 2-isomers of (2-ethylhexyl)bicyclo[2.2.1]hept-2-ene.

Example IV A 1-liter, stainless steel rocker autoclave was charged with50 grams of bicyclo[2.2.l]hept-2-ene and a solution of 2 grams of sodiumin 314 grams of 2,2-diethylpentanol. The reaction mixture was heated to235 C. in 2.5 hours and maintained at 235 C. to 256 C. for 3 hours.After standing at room temperature overnight, the mixture was heated to254 C. in 3 hours and maintained at 243262 C. for hours. The maximumobserved autogenous pressure was 225 p.s.i.g. The mixture was distilledto recover 18 grams of crude 2-(2',2'-diethylpentyl)bicyclo-[2.2.1]hept-2-ene at 79-97 C. and 0.35-1.2 mm. On redistillation, therewere recovered 8 grams of 2-(2',2'- diethylpentyl)bicyclo[2.2.1]hept- 2-ene at 81 C. and 0.40 mm.

Example V A l-liter, stainless steel rocker autoclave was charged with50 grams of bicyclo[2.2.1]hept-2-ene and a solution of 2 grams of sodiumin 500 milliliters of isopropanol. The autoclave was sealed, heated to239 C. in 4 hours and maintained at 239-25 3 C. for 4 hours, duringwhich itme the maximum observed autogenous pressure was 1600 p.s.i.g.The autoclave was cooled to room temperature, opened and the contentswere washed with water and then extracted with isopropylv ether. Afterwaterwashing to a pH of about 7, the ether extract was vacuum distilledto recover 31 grams of diisopropylbicyclo[2.2.l] hept-2-ene at 113118 C.and 92 mm. The product was a mixture of the 1,3- and 1,4-isomers, withthe 1,3-isomer predominating, as determined by nuclear magneticresonance analysis.

Example VI 4 242 C. in 3 hours and maintained at 242-271 C. over 4hours, during which time the maximum observed autogenous pressure was622 p.s.i.g. After cooling to room temperature, the reaction product wasadmixed with water. The resulting mixture was extracted with isopropylether and the ether extract was vacuum distilled to recover 44 grams ofcrude dicyclohexylbicyclo[2.2.1]hept-2-ene at 117-122 C. and 2.22 .mm.The product consisted of the 1,3- and the 1,4-isomers, with the1,3-isorner predominating.

Example VII To a %-inch I.D., 350 cc., tubular reactor were fed 805grams of bicyclo[2.2.1]hept-2-ene and 4195 of a 5 percent solution ofpotassium hydroxide in isopropanol a at a temperature of 290 C. and apressure of 2000 p.s.i.

over a period of 3.4 hours. The reaction product, weighing 4604 grams,was admixed with water, and the aqueous mixture was extracted withhexane. The hexane extract was washed with water to a pH of about 7 andthen distilled. A fraction boiling at 109 C. and 50 mm. was recoveredwhich contained 46 grams of diisopropylbicycloheptene.

What is claimed is:

' 1. The process for producing a substituted bicyclo- I2.2.1]hept-2-enewhich comprises heating at C. to 400 C. a mixture ofbicyclo[2.2.1]hept-2-ene and a monohydric hydrocarbon alcohol havingfrom 1 to 15 carbon atoms, said alcohol having no aliphatic unsaturationand having the hydroxyl group bonded to a carbon atom having at leastone hydrogen atom bonded thereto, in contact with a catalytic amount ofa strong base, for a period of time sufficient to produce saidsubstituted bicyclo[2.2.1lhept-Z-ene.

2. The method for producing a substituted bicyclo- [2.2.1]hept-2-enewhich comprises heating at 150 C. to 400 C. a mixture ofbicyclo[2.2.1]hept-2-ene and a monohydric hydrocarbon primary alcohol offrom 1 to 15 carbon atoms, said alcohol being free from aliphaticunsaturation, in contact with a catalytic amount of a strong base, for aperiod of time sufficient to produce said substitutedbicyclo[2.2.1]hept-2-ene.

3. The process of claim 2, wherein said alcohol is methanol.

4. The process of claim 2, wherein said alcohol is Z-ethylhexanol.

5. The process of claim 2, wherein said alcohol is 2,2-diethylpentanol.

6. The process for producing a substituted bicyclo- [2.2.1]hept-2-enewhich comprises heating at 150 C. to 400 C. a mixture of bicyclo[2.2.1]hept-2-ene and a monohydric hydrocarbon secondary alcohol of from3 to 15 carbon atoms, said alcohol being free of aliphatic unsaturation,in contact with a catalytic amount of a strong base, for a period oftime sufficient to produce said substituted bicyclo[2.2.1]hept-2-ene.

7. The process of claim 6 wherein said alcohol is isopropanol.

8. The process of claim 6 wherein said alcohol is cyclohexanol.

References Cited by the Examiner UNITED STATES PATENTS 2,448,641 9/1948Whitman 260666 2,721,885 10/1955 Pines et al. 260668 2,966,527 12/1960Schmerling 260666 OTHER REFERENCES M. Blanchard et al.: Compt. Rend.,258(9), 25934, 1964.

DELBERT E. GANTZ, Primary Examiner.

1. THE PROCESS FOR PRODUCING A SUBSTITUTED BICYCLO(2.2.1)HEPT-2-ENEWHICH COMPRISES HEATING AT 150*C. TO 400*C. A MIXTURE OFBICYCLO(2.2.1)HEPT-2-ENE AND A MONOHYDRIC HYDROCARBON ALCOHOL HAVINGFROM 1 TO 15 CARBON ATOMS, SAID ALCOHOL HAVING NO ALIPHATIC UNSATURATIONAND HAVING THE HYDROXYL GROUP BONDED TO A CARBON ATOM HAVING AT LEASTONE HYDROGEN ATOM BONDED THERETO, IN CONTACT WITH A CATALYTIC AMOUNT OFA STRONG BASE, FOR A PERIOD OF TIME SUFFICIENT TO PRODUCE SAIDSUBSTITUTED BICYCLO(2.2.1)HEPT-2-ENE.